Relieving steric strain at octahedral platinum(IV): Isomerization and reductive coupling of alkyl and aryl chlorides

Article abstract of DOI:10.1021/om3008019

Oxidation of monocyclometalated platinum(II) complexes results in octahedral platinum(IV) complexes. Depending on the substitution, two different reactions occur: either a simple isomerization, resulting in the exchange of ligand positions, or a reductive coupling of aryl chloride. With a doubly cyclometalated complex, stability of the oxidized form is dependent on isomeric form: whereas the trans isomer is robust, being manipulable in air at room temperature, the cis isomer decomposes at -20 °C and above. Reductive coupling at this cis isomer is 100% selective for alkyl chloride over aryl chloride and is suggested to be a concerted process.

Full text of DOI:10.1021/om3008019

Article
pubs.acs.org/Organometallics
Relieving Steric Strain at Octahedral Platinum(IV): Isomerization and
Reductive Coupling of Alkyl and Aryl Chlorides
Sarah H. Crosby, Guy J. Clarkson, and Jonathan P. Rourke*
Department of Chemistry, Warwick University, Coventry, U.K. CV4 7AL
S
* Supporting Information
ABSTRACT: Oxidation of monocyclometalated platinum(II) com-
plexes results in octahedral platinum(IV) complexes. Depending on
the substitution, two different reactions occur: either a simple
isomerization, resulting in the exchange of ligand positions, or a
reductive coupling of aryl chloride. With a doubly cyclometalated
complex, stability of the oxidized form is dependent on isomeric form:
whereas the trans isomer is robust, being manipulable in air at room
temperature, the cis isomer decomposes at −20 °C and above.
Reductive coupling at this cis isomer is 100% selective for alkyl
chloride over aryl chloride and is suggested to be a concerted process.
INTRODUCTION
RESULTS
■
■
New monomeric cyclometalated phenylpyridine complexes of
platinum(II), 1, with a triphenylphosphine ligand were
synthesized, eq 1. The basic complex (1a) with no additional
Examples of the reductive elimination of alkyl and aryl halides
from metal centers are few and far between. Reports of alkyl
halide elimination are particularly rare: examples include a 1969
report on the pyrolysis of a Pt(IV) complex resulting in the
elimination of methyl chloride,1 a 1994 report that discussed
the competition between C−C and C−I reductive elimination,2
a later paper that indicated that the oxidative addition of methyl
chloride was actually an equilibrium,3 some recent examples of
alkyl-F elimination,4 and our own work with alkyl-chloride
elimination.5 Reports of reductive elimination of aryl halides are
more prevalent, with some synthetic uses being described,6 but
still the number of examples is only on the order of 10.7
We have recently been investigating agostic complexes of,8
C−H activation by,8a,9 and the oxidation of8b,9 a number of
platinum(II) complexes and subsequent reactivity.8c,10 Rarely
do we get a product that does not isomerize or react in some
way. With DMSO ligands we observed initial formation of
sulfur-bound ligands, which isomerized to oxygen-bound
ligands,8b with other complexes we observed dissociation of
ligands to give agostic complexes,8c,10 and with others we
observed reductive elimination.5 It would seem, therefore, that
the initial products of oxidation, the geometry of which is
largely determined by the geometry of the starting square-
planar platinum(II) complexes, are the kinetic products and not
necessarily the most stable. The driving force for isomerization
or reductive elimination can nearly always be ascribed to a
reduction in steric interactions in the newly formed octahedral
platinum(IV) complexes. In this paper we present further
results on reductive elimination reactions of both alkyl and aryl
chlorides that fit very well with this pattern.
functionality on the phenyl pyridine was synthesized via ligand
substitution from a monomeric precursor (L = phenyl pyridine
or DMSO), with the more substituted complexes (1b and 1c)
being synthesized via the splitting of chloride-bridged dimers.
In all cases excellent yields were obtained and the complexes
were fully characterized. An X-ray study of single crystals of 1a
confirms that the triphenylphosphine group is, as expected,11
trans to the pyridine, Figure 1. The similarity of spectroscopic
data and the confirmation of the proximity of the PPh3 rings to
the proton ortho to both F and Pt (from NOE measurements)
allows us to assign the same geometry to all three complexes.
Oxidation of complexes 1 proceeds smoothly with
iodobenzene dichloride at room temperature to give, in all
cases, octahedral platinum(IV) complexes 2, eq 2.
Received: August 20, 2012
Published: September 28, 2012
© 2012 American Chemical Society
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analysis, Figure 2. Since the new species is definitely the fac
isomer, we are able to conclude the initial product was the
depicted mer isomer, 2a.
Figure 1. X-ray structure of 1a. Selected bond lengths (Å) and angles
(deg): Pt(1)−C(12) 2.019(3); Pt(1)−N(1) 2.092(2); Pt(1)−P(1)
2.2269(7); Pt(1)−Cl(1) 2.3719(6); C(6)−C(7) 1.463(4); C(12)−
Pt(1)−N(1) 80.92(10); C(12)−Pt(1)−P(1) 95.34(8); N(1)−Pt(1)−
P(1) 175.60(6); C(12)−Pt(1)−Cl(1) 172.81(8); N(1)−Pt(1)−Cl(1)
92.06(6); P(1)−Pt(1)−Cl(1) 91.61(2); C(2)−N(1)−C(6) 119.7(2);
C(2)−N(1)−Pt(1) 125.74(19); C(6)−N(1)−Pt(1) 114.59(18);
C(11)−C(12)−C(7) 116.7(2); C(11)−C(12)−Pt(1) 129.8(2);
C(7)−C(12)−Pt(1) 113.4(2).
Figure 2. X-ray structure of 3a. Selected bond lengths (Å) and angles
(deg): Pt(1)−C(112) 2.031(3); Pt(1)−N(101) 2.053(3); Pt(1)−
P(201) 2.3144(8); Pt(1)−Cl(1) 2.3171(8); Pt(1)−Cl(3) 2.4031(7);
Pt(1)−Cl(2) 2.4431(8); N(101)−C(102) 1.343(4); N(101)−C(106)
1.361(4); C(106)−C(107) 1.460(5); C(112)−Pt(1)−N(101)
80.90(12); C(112)−Pt(1)−P(201) 92.79(9); N(101)−Pt(1)−
P(201) 92.98(8); C(112)−Pt(1)−Cl(1) 93.48(9); N(101)−Pt(1)−
Cl(1) 174.27(8); P(201)−Pt(1)−Cl(1) 88.36(3); C(112)−Pt(1)−
Cl(3) 86.50(9); N(101)−Pt(1)−Cl(3) 88.10(8); P(201)−Pt(1)−
Cl(3) 178.60(3); Cl(1)−Pt(1)−Cl(3) 90.47(3); C(112)−Pt(1)−
Cl(2) 172.53(9); N(101)−Pt(1)−Cl(2) 93.27(8); P(201)−Pt(1)−
Cl(2) 92.17(3); Cl(1)−Pt(1)−Cl(2) 92.24(3); Cl(3)−Pt(1)−Cl(2)
88.65(3).
Complexes 2 have, like their precursors 1, the phosphine
trans to the pyridine and now have a mer arrangement of the
three chlorides. This particular isomer can be easily identified
from the proton NMRs of the substituted complexes 2b and 2c,
as the alternative, with a fac arrangement of the three chlorides
(like 3a, below), would have each of the protons of each CH2
group of the R chain exhibiting a unique resonance. The
sterically crowded alternative mer isomer with the phosphine
trans to the cyclometalated carbon can be ruled out on two
grounds: first, NOE experiments confirm the proximity of the
triphenyl phosphine to the cyclometalated ring, and second, the
observed 195Pt−31P coupling constants are larger than that
expected for a P trans to a C. For the case of 2a, the argument
that rules out the alternative mer isomer is valid, but the first
argument cannot be used. However, we observe a slow
isomerization of the initially formed product to a new Pt(IV)
species that has the same pattern of NMR signals, eq 3. We
The isomerization of 2a to 3a takes about 2 weeks in dilute
solution at room temperature with the same product formed in
chloroform or acetone; reaction temperature does not affect the
product formed. A different isomerization was seen with
substituted complexes 2b and 2c. In both cases a reductive
coupling was seen, accompanied by a color change from yellow
to essentially colorless. Evidence for the reduction comes from
a dramatic change in the 195Pt chemical shift (e.g., −1661 ppm
for 2b to −3440 for 4b) and in the 195Pt−31P coupling constant
(e.g., form 2619 Hz for 2b to 3765 for 4b). Evidence for the
cleavage of the Pt−C bond comes from the loss of 19F−195Pt
coupling in the reduced species, but the coupling pattern
1
(1H−1H and H−19F) of the protons in that ring suggests
replacement of Pt by another group. Evidence that this other
group is a chloride comes from the mass spectra of complexes
4: very strong signals that can be assigned to a chlorinated
version of the phenyl pyridine are found in the positive ion
mass spectrum, with high-resolution spectra confirming the
elemental composition. The fact that each of the protons of
each CH2 group of the R chain does exhibit a unique resonance
1
in the H NMR allows us to assign a cis geometry to the new
complex, but one in which there is, on the NMR time scale,
restricted rotation of the pyridine fragment about the N−Pt
bond.12
Taken together, this evidence allows us to assign the
structures depicted as 4b and 4c to the new Pt(II) species,
were able to unequivocally assign the fac geometry to this new
complex 3a, as we were able to grow crystals suitable for X-ray
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eq 4. The aryl chloride reductive coupling reaction seen here
was rather slow, with reaction times being on the order of 4
weeks at room temperature.
significantly affect the rate of the reductive coupling, but
seemed to retard the rate of isomerization. Addition of extra
chloride (in the form of Bu4NCl) did not appear to affect either
reaction rate.
We also investigated the oxidation of the related complex 5,
which is derived from the tert-butyl version of the phenyl
pyridine present in complexes 1−4.8a,d,10 Oxidation of 5 in
chloroform proceeds cleanly and rapidly at −40 °C to give a
single Pt(IV) species, identified as the complex cis-6, eq 5. The
Complex 7 could not, however, be fully characterized: it lost
triphenylphosphine when attempts were made to isolate it and
formed (among other unidentified products) the previously
characterized 8. Further reactivity of complex 7 was observed if
it was treated with more oxidant: NMR signals consistent with
new complexes 9 were identified before they lost triphenyl-
phosphine to give (among other unidentified products) the
previously characterized 10, eq 7
product 6 could easily be identified as the cis isomer from the
inequivalence of both the CH2 protons and the Me groups of
1
the cyclometalated alkyl group in the H NMR (signals of
relative intensity 1:1:3:3) and the NOE interactions of only one
of the CH2 protons and of only one of the Me groups with the
triphenylphosphine. Due to its reactivity, we were unable to
isolate samples of cis-6 and fully characterize it, but we were
able to record complete NMR spectra at low temperature in
solution. Complex cis-6 underwent further reactions: it
isomerized to trans-6, which showed single resonances for the
CH2 protons and for the Me groups (relative intensity 2:6), at
temperatures above −20 °C, eq 5.
DISCUSSION
■
As shown in eq 2, complexes 2 form, upon initial oxidation,
with all the previously bound species in the same relative
positions as the starting complexes 1. Such a result can be
thought of as arising either from the delivery of the two new
chloride ligands to the same face of the platinum(II) square
plane, with the existing chloride moving, or from the delivery of
the two new chlorides separately to opposite sides of the
molecule.9b,13 The isomerization of 2a to 3a depicted in eq 3
can be seen as providing steric relief, as the large phosphine
ligand is moved out of the plane of the metalated pyridine to a
position in 3a where it is less encumbered. This isomerization
has many similarities to isomerization reactions we have seen
before with other Pt(IV) complexes,8b,9,10 and our observations
here add nothing to the lessons learned there.
The presence of the alkyl chains in 2b and 2c would not be
expected to electronically destabilize the Pt(IV) center in 2b
and 2c compared with 2a; if anything, the electron-releasing
chains might be expected to help stabilize the high oxidation
state. However, we might expect more steric crowding in
complexes 2b and 2c compared with 2a and a greater driving
force toward isomerization. Though the final products are ones
that arise from reductive elimination, presumably an isomer-
ization to unseen 3b and 3c is also possible for complexes 2b
and 2c. Whether the additional steric interactions of the alkyl
chain affect their stability adversely and the unseen 3b and 3c
Complex trans-6 can be isolated and manipulated in air at
room temperature and was fully characterized. In addition to
the isomerization to trans-6, complex cis-6 also undergoes a
reductive coupling, but, unlike complexes 2b and 2c, it is an
alkyl chloride coupling rather than an aryl chloride coupling.
The coupling we see takes place much more rapidly than that
seen with complexes 2b and 2c and takes place at temperatures
above −20 °C: it is complete in minutes in any sample taken to
0 °C. The initial product of reduction can be identified as 7: a
single peak in the 31P NMR with a 195Pt−31P coupling constant
consistent with a Pt(II) species and a 195Pt chemical shift
1
consistent with Pt(II) and two H resonances in the ratio 2:6
(neither with Pt satellites) for the chloroalkyl group. In solution
at −20 °C the ratio of 7 to trans-6 produced is roughly 3:1. The
production of 7 and trans-6 appears to be via parallel and
competing reactions. Using chloroform as the solvent (to
minimize the extent of the isomerization), we sought to
extricate some of the reaction parameters. However it proved
impossible to satisfactorily separate the kinetics of the two
reactions. Addition of extra phosphine did not appear to
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rapidly reductively eliminate or whether complexes 2b and 2c
directly reductively eliminate to 4b and 4c cannot be
determined from our current experiments. Either way, the
fact that neither 2a nor 3a shows any tendency to reductively
eliminate demonstrates how fine the balance between the
relative stabilities of the Pt(IV) and Pt(II) centers in the alkyl-
substituted complexes really is.
If we consider the mechanism of reductive elimination that
operates to give complexes 4b and 4c, it is generally accepted
that a concerted route for aryl halide reductive eliminations
exists. Recent work on aryl oxygen14 and aryl bromine15
eliminations and demonstrations of the involvement of dimeric
Pd(III) complexes16 in eliminations all invoke concerted
routes: our work here fits in nicely with these results, and we
would expect a concerted mechanism to operate for reaction 4.
For such a process, we would need with cis C and Cl to form
the new bond and, further, we might expect the coupling
chloride to have its Pt−Cl bond parallel with the p orbitals of
the π system of the aryl ring on which the C atom is
located.7b,17 Such an arrangement is present in both complexes
2 and 3 and cannot therefore be used to distinguish between
complexes 2b and 2c isomerizing first or directly reductively
eliminating.
the trans-6 is favored over both the cis-6 and the coupled
product, but that there is a low-energy route from cis-6 to 7,
one that is not available to trans-6.
The SN2 type of oxidative addition of alkyl halides to late
transition metals has been well established,19 and thus the
microscopic reverse reaction would be expected to initiate with
the dissociation of halide from the metal, with this liberated
halide then combining with the eliminating alkyl group. It is
hard to see how the difference in rates of reductive coupling at
cis- and trans-6 could fit with the microscopic reverse of the SN2
process, and we were able, with a detailed kinetic analysis (and
other reactions), to definitively assign a unimolecular concerted
mechanism to the reductive coupling for the DMSO analogue.5
With the triphenylphosphine complex 6, we see the same
isomeric dependence of the reductive elimination and see no
reason not to assign a concerted mechanism to this new
example. With a simplistic model of a concerted process, we
can see in the cis orientation a chloride trans to the N can
couple easily with the alkyl group, whereas in the trans it
cannot, Figure 3. Such an isomeric dependence of reaction
route would not exist for an SN2-type process.
If we consider the oxidation of doubly cyclometalated 5
shown in eq 5, we see the initial formation of only a single
isomer of the product, cis-6, which can be thought of as arising
from delivery of both of the new chlorides to the same face of
5, with the phosphine being moved out of the plane of the
phenyl pyridine. In our previous work we had established that
the solvent was often noninnocent,5,9b,10 particularly if acetone
or DMSO was used, and for this reason we used chloroform as
the reaction solvent. That doubly cyclometalated 5 gives only
cis-6 is not unexpected: the equivalent complex with a DMSO
ligand in place of the triphenylphosphine gave predominately
the cis isomer in the equivalent reaction.5 We see cis-6 isomerize
to trans-6 on warming to −20 °C, and all previous work on the
isomerization of octahedral d6 complexes of Pt(IV) indicates a
likely dissociative mechanism;18 our observation of a retarding
of the rate with added phosphine is consistent with this
mechanism. The isolation of unreactive trans-6 has parallels
with our previously reported DMSO complexes, where we also
saw an isomerization of cis to trans and were again able to
isolate and characterize the trans isomer.
The reductive elimination reaction we observe with cis-6, the
coupling of a chloride with the cyclometalated alkyl group to
give 7, also has precedent in our earlier work: with the DMSO
complex we saw the same parallel reaction where the cis
reductively eliminated an alkyl chloride group. The triphenyl-
phosphine complex cis-6 is more prone to reductive elimination
than the DMSO equivalent: whereas the DMSO complex
began to react only at temperatures above 0 °C, the
triphenylphosphine complex begins to reductively eliminate
above −20 °C. Such an observation is entirely consistent with
the increase steric bulk of the triphenylphosphine compared
with the DMSO.
Figure 3. In the cis isomer (left) the chloride can couple with the alkyl
group with little disruption to the rest of the molecule, whereas in the
trans isomer (right) an initial steric clash with a hydrogen needs a
substantial rearrangement of the cyclometalated ring in order to
facilitate the coupling.
Apart from our previous work, there has been no other
examples of a concerted mechanism for alkyl chloride reductive
elimination. Sterically crowded platinum complexes have been
shown to undergo concerted alkyl fluoride reductive elimi-
nation when treated with XeF2 to generate a putative dicationic
Pt(IV) center4a (earlier work with XeF2 and platinum showing
benzylic-F elimination did not suggest a mechanism4c), and
another more recent example suggests that a concerted
mechanism might be working for an alkyl-F coupling at
Pd(IV).4b A few other studies on systems related to the work
presented here have been conducted, but it is the reductive
elimination of alkyl oxygen groups at Pt(IV) that is of most
relevance: an SN2-type process has been demonstrated with
unconstrained ligand systems,20 but a concerted process in a
solitary example with chelating groups.21 Our work here
therefore fits in with an emerging pattern of concerted alkyl-X
reductive elimination reactions where steric factors force the
coupling groups into close proximity.
The reductive elimination we observe is completely selective
for the C(sp3)−Cl coupling over C(sp2)−Cl coupling and can
be attributed to the thermodynamics of the weaker M−C bond
being cleaved. Once formed, complex 7 can lose triphenyl-
phosphine to form complex 8, where the last ligand position at
platinum is taken up by the chloride attached to the tert-butyl
group. Presumably the entropic factors associated with the
chelating of this group to the central metal, coupled with a
reduction in steric crowding, are sufficient to overcome the
replacement of the strong Pt−P bond with a weaker Pt−Cl
bond. If we compare the situation with our previously reported
With the equivalent DMSO complexes, we were intrigued as
to why the cis complex reductively eliminated, but the trans
remained stable. There, provisional DFT studies had indicated
that there was not a great thermodynamic preference for trans
over cis (∼4 kJ mol−1). With the triphenylphosphine complexes
6 and 7 we see a similarly small preference for the trans over the
cis (∼2 kJ mol−1), with both disfavored by some 10 kJ mol−1
over the reductively coupled product 7. Thus it cannot be that
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Anal. Found (Expected): C 51.93 (52.38), H 3.54 (3.33), N 1.89
(2.11).
DMSO complexes, it is interesting to note that the equivalent
of 7 was not seen, and only 8 was observed. Further oxidation
of 7 or 8 (or indeed a mixture of 7 and 8) ultimately gives the
same product: the previously characterized 10, where the
additional steric congestion of the alternative products, cis- and
trans-9, is relieved.
Synthesis of Complexes 1b and 1c. Chloride-bridged dimer
((F-PhPy-R)PtCl)2 (0.0728 g, 8.45 × 10−5 mol, 1 equiv) was dissolved
in acetone, and PPh3 (0.0443 g 1.69 × 10−4 mol, 2 equiv) added. The
solution was stirred at room temperature for 1 h. The solvent was
removed to give 1b. Yield: 0.0550 g, 7.94 × 10−5 mol, 94%. Similarly
1c was produced in 92% yield.
CONCLUSIONS
■
Square-planar platinum(II) complexes evidently experience
increased steric strain upon oxidation to octahedral platinum-
(IV) species. We have demonstrated that the balance between
relieving this strain through the simple expedient of ligand
rearrangement or through reductive coupling of two of the
groups is very fine. In complex cis-6, steric strain is relieved
through a reductive coupling that is totally selective for alkyl
chloride over an alternative aryl chloride elimination.
3
δH (400 MHz, 298 K, CDCl3): 7.73 (6H, m, Ho), 7.66 (1H, t, J =
EXPERIMENTAL SECTION
7.8 Hz, He), 7.46 (1H, d, 3J = 7.9 Hz, Hf), 7.21−7.40 (10H, m,
Hp, q and i), 7.09 (1H, d, 3J = 7.8 Hz, Hd), 6.52 (1H, td, 3JH−H, H−F = 8.4
■
General Procedures. All chemicals were used as supplied, unless
noted otherwise. All NMR spectra were obtained on a Bruker Avance
400, 500, or 600 MHz spectrometer and are referenced to external
TMS, assignments being made with the use of decoupling, NOE, and
the DEPT and COSY pulse sequences. 1H−19F and 1H−195Pt
correlation spectra were recorded using a variant of the HMBC
pulse sequence. 19F chemical shifts are quoted from the directly
observed signals (referenced to external CFCl3), whereas the 195Pt
chemical shifts quoted are taken from the 2D HETCOR spectra
(referenced to external Na2PtCl6). All elemental analyses were
performed by Warwick Analytical Service. Starting platinum complexes
were prepared as previously reported.8a,9
Synthesis of Complex 1a. Pendant phenylpyridine complex (F-
PhPy-H)Pt(PhPy)Cl (0.0201 g, 3.49 × 10−5 mol, 1 equiv) and PPh3
(0.0092 g, 3.49 × 10−5 mol, 1 equiv) were dissolved in acetone (15
mL) and allowed to stir at room temperature for 5 h. The solvent was
removed and the residue dissolved in DCM. The solution was washed
with 2.5 M HCl (2 × 20 mL) and dried over MgSO4, and the solvent
was removed. Yield: 0.018 g, 2.65 × 10−5 mol, 76%. A crystal suitable
for X-ray diffraction was grown by slow evaporation of solvent from a
chloroform solution. Details are given in Table 1 (SI).
4
3
4
Hz, J = 2.5 Hz, Hj), 6.16 (1H, ddd, JH−F = 10.8 Hz, JH−P = 3.5 Hz,
4JH−H = 2.5 Hz, 3JH−Pt = 60 Hz, Hl), 3.60 (2H, q, 3J = 7.5 Hz, Hb), 1.33
3
(3H, t, J = 7.5 Hz, Ha) ppm. δC (100 MHz, 298 K, CDCl3): 168.0
(Cc), 162.8 (Cg), 160.5 (d, JC−F = 252 Hz, Ck), 143.6 (d, JC−F = 6
Hz, Ch), 141.8 (d, JC−F = 2 Hz, Cm), 138.0 (Ce), 134.2 (d, JC−P
1
4
3
2
=
4
1
11.5 Hz, Co), 129.7 (d, JC−P = 3 Hz, Cq), 128.8 (d, JC−P = 63 Hz,
Cn), 127.0 (d, 3JC−P = 12.3 Hz, Cp), 124.3 (d, 3JC−F = 8.4 Hz, 3JC−Pt
=
2
3
38 Hz, Ci), 122.2 (dd, JC−F = 20.7 Hz, JC−P = 7.7 Hz, Cl), 121.1 (d,
4JC−P = 4.6 Hz, Cd), 114.2 (Cf), 109.3 (d, JC−F = 23 Hz, Cj), 31.1
2
(Cb), 14.1 (Ca) ppm. δF (282 MHz, 298 K, CDCl3): −112.0 (4JF−Pt
=
64 Hz) ppm. δP (121 MHz, 298 K, CDCl3): 21.4 (1JP−Pt = 4449 Hz)
ppm. δPt (298 K, CDCl3): −3943 (d, 1JPt−P = 4497 Hz) ppm. HR-MS
(ESI): m/z 656.1425 calculated for C31H26FNP194Pt = (M − Cl)+
656.1408. Anal. Found (Expected): C 53.67 (53.72); H 3.88 (3.78); N
2.42 (2.02).
δH (400 MHz, 298 K, CDCl3): 7.71−7.76 (6H, m, Hp), 7.62 (1H, t,
3
3J = 7.8 Hz, Hf), 7.45 (1H, d, J = 8 Hz, Hg), 7.28−7.38 (10H, m,
H
j, q and r), 7.06 (1H, d, 3J = 7.5 Hz, He), 6.52 (1H, td, 3JH−H, H−F = 8.3
Hz, 4J = 2.5 Hz, Hk), 6.16 (1H, ddd, 3JH−F = 10.8 Hz, 4JH−P = 2.7 Hz,
4JH−H = 2.5 Hz, JH−Pt = 62 Hz, Hm), 3.57−3.60 (2H, m, Hc), 1.88
(2H, sextet, J = 7.5 Hz, Hb), 0.88 (3H, t, J = 7.5 Hz, Ha) ppm. δC
(100 MHz, 298 K, CDCl3): 166.6 (Cd), 163.0 (d, JC−P = 3 Hz, Ch),
3
δH (400 MHz, 298 K, CDCl3): 9.78 (1H, ddd, 3J = 5.8 Hz, 4J = 1.3
3
3
4
3
4
3
Hz, JH−P = 4.1 Hz, Ha), 7.80 (1H, td, J = 7.8 Hz, J = 1.6 Hz, Hc),
7.71−7.75 (6H, m, Hn), 7.62 (1H, d, 3J = 8 Hz, Hd), 7.43 (1H, dd, 3J =
8.5 Hz, 4JH−F = 5.8 Hz, Hg), 7.38 (3H, td, 3J = 7.4 Hz, 4J = 2 Hz, Ho),
7.30−7.33 (6H, m, Hm), 7.20−7.23 (1H, m, Hb), 6.59 (1H, td,
1
4
4
160.5 (dd, JC−F = 252 Hz, JC−P = 3 Hz, Cl), 143.6 (t, JC−F = 6 Hz,
3JC−P = 6 Hz, Ci), 141.7 (d, JC−F = 2 Hz, Cn), 137.9 (Cf), 134.1 (d,
3
2JC−P = 10 Hz, Cp), 129.7 (d, 4JC−P = 2.3 Hz, Cr), 128.9 (d, 1JC−P = 61
3JH−H, H−F = 8.4 Hz, J = 2.5 Hz, Hh), 6.23 (1H, dt, JH−F = 11.2 Hz,
4
3
3
3
Hz, Co), 127.0 (d, JC−P = 11.5 Hz, Cq), 124.3 (d, JC−F = 9 Hz, Cj),
4JH−H, H−P = 2.8 Hz, JH−Pt = 63 Hz, Hj) ppm. δC (100 MHz, 298 K,
3
2
3
122.1 (dd, JC−F = 20 Hz, JC−P = 7 Hz, Cm), 121.9 (Ce), 114.3 (Cg),
109.2 (d, 2JC−F = 23 Hz, Ck), 39.4 (Cc), 23.5 (Cb), 12.8 (Ca) ppm. δF
(375 MHz, 298 K, CDCl3): −112.0 (4JF−Pt = 60 Hz) ppm. δP (161
MHz, 298 K, CDCl3): 21.1 (1JP−Pt = 4446 Hz) ppm. δPt (298 K,
1
7
CDCl3): 163.7 (Ce), 161.8 (d, JC−F = 251 Hz, Ci), 148.3 (d, JC−F
=
2
3
4.6 Hz, JC−Pt = 24 Hz, Ca), 143.6 (d, JC−F = 6 Hz, Ck), 140.8 (Cf),
138.5 (Cc), 134.3 (Cn), 129.9 (Co), 129.0 (Cl), 127.0 (Cm), 123.9 (d,
3JC−F = 9.2 Hz, 3JC−Pt = 52 Hz, Cg), 123.1 (d, 2JC−F = 21 Hz, Cj), 120.7
(3JC−Pt = 23 Hz, Cb), 117.2 (3JC−Pt = 29 Hz, Cd), 109.2 (d, 2JC−F = 23
Hz, Ch) ppm. δF (375 MHz, 298 K, CDCl3): −110.1 (4JF−Pt = 54 Hz)
ppm. δP (121 MHz, 298 K, CDCl3): 22.9 (1JP−Pt = 4265 Hz) ppm. δPt
1
CDCl3): −3923 (d, JPt−P = 4466 Hz) ppm. HR-MS (ESI): m/z
670.1573 calculated for C32H28FNP194Pt = (M − Cl)+ 670.1565. Anal.
Found (Expected): C 53.82 (54.36); H 3.45 (3.99); N (1.96 (1.98).
Synthesis of Complexes 2a and 3. Complex 1a (0.011 g, 1.65 ×
10−5 mol, 1 equiv) was dissolved in CDCl3, and (dichloroiodo)-
benzene (0.0045 g, 1.65 × 10−5 mol, 1 equiv) was added at room
1
(298 K, CDCl3): −4160 (d, JPt−P = 4283 Hz) ppm. HR-MS (ESI):
m/z 628.1091 calculated for C29H22FNP194Pt = (M − Cl)+ 628.1095.
7260
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temperature. After 10 min the solvent was removed and the product
washed with pet ether 40−60 to give pure complex 2a. Yield: 0.011 g,
1.49 × 10−5 mol, 90%.
1
170.0 (Cc), 162.8 (Cg), 160.8 (d, JC−F = 253.5 Hz, Ck), 141.1 (d,
4JC−F = 2.2 Hz, Ch), 139.9 (Cm), 139.8 (Ce), 136.1 (d, 2JC−P = 8.5 Hz,
3JC−Pt = 17 Hz, Co), 131.8 (d, 4JC−P = 2.7 Hz, Cq), 127.8 (d, 3JC−P = 12
3
1
Hz, Cp), 126.7 (d, JC−F = 8.5 Hz, Ci), 126.5 (d, JC−P = 69 Hz, Cn),
123.4 (d, 4JC−P = 6.7 Hz, 3JC−Pt = 19 Hz, Cd), 122.6 (dd, 2JC−F = 24 Hz,
3JC−P = 3 Hz, 2JC−Pt = 51 Hz, Cl), 117.9 (d, 4JC−P = 3.3 Hz, 3JC−Pt = 19
δH (400 MHz, 273 K, CDCl3): 10.00 (1H, td, 3J = 6 Hz, 4J = 1 Hz,
3JH−Pt = 30 Hz, Ha), 8.09 (6H, m, Hm), 7.97 (1H, td, 3J = 7.8 Hz, 4J =
1.3 Hz, Hc), 7.89 (1H, d, 3J = 8 Hz, Hd), 7.71 (1H, m, Hg), 7.53 (3H,
2
Hz, Cf), 113.2 (d, JC−F = 22.5 Hz, Cj), 30.8 (Cb), 15.1 (Ca) ppm. δF
3
m, Ho), 7.44−7.48 (7H, m, Hb and Hn), 6.89 (1H, td, JH−H, H−F = 8
(375 MHz, 298 K, CDCl3): −108.5 (4JF−Pt = 34 Hz) ppm. δP (161
Hz, 4J = 2.6 Hz, Hh), 6.50 (1H, dt, 3JH−F = 10 Hz, 4JH−H, H−P = 2.6 Hz,
3JH−Pt = 32 Hz, Hj) ppm. δC (100 MHz, 298 K, CDCl3): 160.0 (Ce),
MHz, 298 K, CDCl3): −1.6 (1JP−Pt = 2619 Hz) ppm. δPt (298 K,
1
CDCl3): −1661 (d, JPt−P = 2580 Hz) ppm. Anal. Found (Expected):
3
4
146.6 (d, JC−P = 6 Hz Ca), 139.3 (Cc), 139.1 (d, JC−F = 6 Hz, Cf),
C 48.61 (48.74); H 3.02 (3.43); N 2.21 (1.83).
3
2
Complex 1c (0.019 g, 2.69 × 10−5 mol, 1 equiv) was dissolved in
CDCl3, and (dichloroiodo)benzene (0.0074 g, 2.69 × 10−5 mol, 1
equiv) was added at room temperature. After 10 min the solvent as
removed and the product washed with pet ether 40−60 to give pure
complex 2c. Yield: 0.0171 g, 2.20 × 10−5 mol, 82%.
137.8 (d, JC−F = 2 Hz, Ck), 134.8 (d, JC−P = 9 Hz, Cm), 130.9 (d,
4JC−P = 2 Hz, Co), 126.6 (d, 3JC−P = 12 Hz, Cn), 125.6 (d, 3JC−F = 9 Hz,
1
4
Cg), 125.4 (d, JC−P = 66 Hz, Cl), 122.5 (d, JC−P = 5 Hz, Cb), 120.7
(dd, 2JC−F = 24 Hz, 3JC−P = 3 Hz, Cj), 119.4 (d, 4JC−P = 3 Hz, 3JC−Pt
=
2
21 Hz, Cd), 112.2 (d, JC−F = 23 Hz, Ch) ppm. δF (375 MHz, 273 K,
CDCl3): −105.5 (4JF−Pt = 30 Hz) ppm. δP (161 MHz, 273 K, CDCl3):
−3.2 (1JP−Pt = 2494 Hz) ppm. δPt (298 K, CDCl3): −1916 (d, 1JPt−P
=
2494 Hz) ppm.
NMR spectra of the sample were collected over a number of days,
showing the disappearance of 2a and appearance of a new species
identified as 3. Crystals of 3 suitable for single-crystal analysis were
grown by slow evaporation of solvent from a chloroform solution. X-
ray data are given in Table 1 (SI).
δH (300 MHz, 298 K, CDCl3): 7.92−7.98 (6H, m, Hp), 7.78 (1H, t,
3J = 7.6 Hz, Hf), 7.68 (1H, br d, 3J = 6.7 Hz, Hg), 7.53 (1H, dd, 3J = 8.5
4
Hz, JH−F = 5.6 Hz, Hj), 7.45−7.50 (3H, m, Hr), 7.31−7.39 (6H, m,
3
3
Hq), 7.18 (1H, br d, J = 6.8 Hz, He), 6.79 (1H, td, JH−H, H−F = 8.3
Hz, 4J = 2.3 Hz, Hk), 6.40 (1H, ddd, 3JH−F = 9.7 Hz, 4J = 2.5 Hz, 4JH−P
= 3.6 Hz, JH−Pt = 40 Hz, Hm), 3.81−3.86 (2H, m, Hc), 1.81 (2H,
sextet, J = 7.2 Hz, Hb), 0.94 (3H, t, J = 7.2 Hz, Ha) ppm. δC (100
3
3
3
1
3
4
MHz, 298 K, CDCl3): 168.8 (Cd), 162.3 (Ch), 160.8 (d, JC−F = 254
δH (500 MHz, 298 K, CDCl3): 9.29 (1H, dd, J = 6.3 Hz, J = 1.3
Hz, Cl), 141.0 (d, 4JC−F = 2.5 Hz, Ci), 139.7 (Cn), 139.5 (Cf), 136.2 (d,
2JC−P = 8.5 Hz, 3JC−Pt = 20 Hz, Cp), 131.8 (d, 4JC−P = 3 Hz, Cr), 129.4
3
3
4
Hz, JH−Pt = 30 Hz, Ha), 7.63 (1H, td, J = 7.8 Hz, J = 1.4 Hz, Hc),
3
7.60 (1H, m, Hj), 7.48−7.51 (6H, m, Hm), 7.46 (1H, dd, J = 8.8 Hz,
(d, 1JC−P = 63 Hz, Co), 127.7 (d, 3JC−P = 12 Hz, Cq), 126.8 (d, 3JC−F
=
4JH−F = 5.4 Hz, Hg), 7.38−7.41 (1H, m, Hd), 7.32−7.35 (3H, m, Ho),
8 Hz, Cj), 124.0 (d, 4JC−P = 7 Hz, 3JC−Pt = 18 Hz, Ce), 122.6 (dd, 2JC−F
= 23.5 Hz, 3JC−P = 3 Hz, Cm), 117.9 (d, 4JC−P = 3.3 Hz, Cg), 113.2 (d,
2JC−F = 22 Hz, Ck), 39.1 (Cc), 24.4 (Cb), 13.5 (Ca) ppm. δF (282 MHz,
298 K, CDCl3): −109.3 (4JF−Pt = 32 Hz) ppm. δP (121 MHz, 298 K,
CDCl3): −1.8 (1JP−Pt = 2622 Hz) ppm. δPt (298 K, CDCl3): −1661 (d,
1JPt−P = 2657 Hz) ppm. Anal. Found (Expected): C 49.01 (49.40); H
3.21 (3.63); N 1.61 (1.80).
3
4
7.14−7.18 (6H, m, Hn), 6.86 (1H, td, J = 7.0 Hz, J = 1.4 Hz, Hb),
6.78 (1H, td, 3JH−H, H−F = 8.3 Hz, 4J = 2.4 Hz, Hh) ppm. δF (375 MHz,
298 K, CDCl3): −101.8 (4JF−Pt = 28 Hz) ppm. δP (202 MHz, 298 K,
CDCl3): −8.6 (1JP−Pt = 2303 Hz) ppm. δPt (298 K, CDCl3): −2102 (d,
1JPt−P = 2354 Hz) ppm. HR-MS (ESI): m/z 756.0080 calculated for
C29H2235Cl3FNNaP194Pt = (M + Na)+ 756.0058, 698.0490 calculated
for C29H2235Cl2FNP194Pt = (M − Cl)+ 698.0472. Anal. Found
(Expected): C 46.94 (47.33); H 3.32 (3.01); N 1.72 (1.90).
Synthesis of Complexes 2b and 2c. Complex 1b (0.015 g, 2.16
× 10−5 mol, 1 equiv) was dissolved in CDCl3, and (dichloroiodo)-
benzene (0.0060 g, 2.16 × 10−5 mol, 1 equiv) was added at room
temperature. After 10 min the solvent was removed and the product
washed with pet ether 40−60 to give pure complex 2b. Yield: 0.0144 g,
1.88 × 10−5 mol, 87%.
Synthesis of Complexes 4b and 4c. Chloroform solutions of 2b
1
and 2c were monitored via H, 19F, and 31P NMR spectra over a
period of one month. Once all the sample had isomerized, the solvent
was removed to give analytically pure samples of 4b or 4c.
3
δH (400 MHz, 298 K, CDCl3): 7.92 (6H, m, Ho), 7.75 (1H, t, J =
3
3
7.6 Hz, He), 7.63 (1H, d, J = 8 Hz, Hf), 7.48 (1H, dd, J = 8.5 Hz,
4JH−F = 5.6 Hz, Hi), 7.43 (3H, m, Hq), 7.31 (6H, td, J = 7.6 Hz, J =
3.4 Hz, Hp), 7.13 (1H, br d, 3J = 7.6 Hz, Hd), 6.74 (1H, td, 3JH−H, H−F
= 8.2 Hz, 4J = 2.4 Hz, Hj), 6.32 (1H, ddd, 3JH−F = 9.8 Hz, 4J = 2.4 Hz,
3
4
4JH−P = 3.7 Hz, JH−Pt = 39.6 Hz, Hl), 3.87 (2H, q, J = 7.4 Hz, Hb),
3
3
3
1.27 (3H, t, J = 7.4 Hz, Ha) ppm. δC (100 MHz, 298 K, CDCl3):
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Article
2
δH (400 MHz, 298 K, CDCl3): 8.14 (1H, dd, 3J = 8.6 Hz, 4JH−F = 6
CDCl3): 141.9 (Cf), 135.3 (d, JC−P = 9.2 Hz, Ck), 131.8 (Cm), 128.5
3
3
Hz, Hk), 7.76 (1H, t, J = 7.8 Hz, Hg), 7.38−7.44 (6H, m, Hq), 7.36
(d, JC−P = 11.5 Hz, Cl), 121.8 (Cj), 118.2 (Ce), 117.8 (Cg), 112.1
(1H, br d, 3J = 7.8 Hz, Hf), 7.34 (3H, dd, 3J = 7.4 Hz, 4J = 2 Hz, Hs),
7.25−7.30 (8H, m, Hh, Hn and Hr), 7.04 (1H, td, 3JH−H, H−F = 8.3 Hz,
4J = 2.6 Hz, Hl), 4.08 (1H, dq, 2J = 16 Hz, 3J = 7.8 Hz, Hb/c), 3.79 (1H,
(Ci), 44.8 (Ca/b), 37.6 (Cc), 30.1 (Cd) ppm. δF (375 MHz, 233 K,
CDCl3): −109.6 (4JF−Pt = 43 Hz) ppm. δP (161 MHz, 233 K, CDCl3):
0.5 (1JP−Pt = 2993 Hz) ppm. δPt (233 K, CDCl3): −2425 (d, JP−Pt
=
1
3
dq, 2J = 16 Hz, 3J = 7.8 Hz, Hb/c), 1.50 (3H, t, J = 7.6 Hz, Ha) ppm.
3026 Hz) ppm.
1
As the temperature of the reaction mixture was increased, three new
δC (100 MHz, 298 K, CDCl3): 165.0 (Ce), 162.7 (d, JC−F = 253 Hz,
species were observed with a multiple set of peaks in the H, 19F, 31P,
1
4JC−P = 3 Hz, Cm), 156.9 (Ci), 138.1 (Cg), 136.2 (d, 3JC−F = 9 Hz, Ck),
and 195Pt NMR spectra. Column chromatography, loading, and eluting
with chloroform resulted in the isolation of complex 8 as fraction 1
(48% based on starting Pt complex) and trans-6 as fraction 2 (17%
based on starting Pt complex). No other products could be isolated
and fully characterized.
2
4
134.6 (d, JC−P = 10 Hz, Cq), 130.7 (d, JC−P = 3 Hz, Cs), 128.6 (d,
1JC−P = 64 Hz, Cp), 127.8 (d, JC−P = 11.5 Hz, Cr), 126.0 (d, JC−P
3.8 Hz, Ch), 123.9 (d, JC−P = 3.8 Hz, Cf), 116.8 (d, JC−F = 24.5 Hz,
Cn), 113.1 (d, JC−F = 19 Hz, Cl), 31.8 (Cd), 13.0 (Ca) ppm. δF (375
=
3
4
4
2
2
MHz, 298 K, CDCl3): −110.2 ppm. δP (161 MHz, 298 K, CDCl3):
−1.7 (1JP−Pt = 3765 Hz) ppm. δPt (298 K, CDCl3): −3440 (d, 1JPt−P
=
3797 Hz) ppm. HR-MS (ESI): m/z 784.0397 calculated for
C31H2635Cl3FNNaP194Pt = (M + Na)+ 784.0371, 726.0792 calculated
for C31H2635Cl2FNP194Pt = (M − Cl)+ 726.0785, 236.0644 calculated
for C13H1235ClFN = (Ligand + H)+ 236.0637. Anal. Found
(Expected): C 48.55 (48.74); H 3.62 (3.43); N 1.99 (1.83).
δH (500 MHz, 298 K, CDCl3): 7.83−7.87 (7H, m, Hj and Hp), 7.80
3
3
4
(1H, t, J = 8 Hz, Hf), 7.67 (1H, dd, J = 7.8 Hz, J = 2.4 Hz, Hg),
7.49−7.51 (3H, m, Hr), 7.43−7.47 (6H, m, Hq), 7.35 (1H, dd, 3JH−F
=
8.8 Hz, 4J = 2.7 Hz, 3JH−Pt = 28.5 Hz, Hm), 7.01 (1H, dd, 3J = 7.8 Hz, 4J
= 2.5 Hz, He), 6.87 (1H, td, 3JH−H, H−F = 8.7 Hz, 4J = 2.7 Hz, Hk), 2.36
2
(2H, s, JH−Pt = 47.6 Hz, Hb), 1.44 (6H, s, Ha) ppm. δC (125 MHz,
3
4
δH (400 MHz, 298 K, CDCl3): 8.14 (1H, dd, J = 8.7 Hz, JH−F
=
3
298 K, CDCl3): 177.6 (Cd), 167.5 (d, JC−F = 5.7 Hz, Cn), 163.3 (d,
3
6.2 Hz, Hn), 7.73 (1H, t, J = 7.8 Hz, Hj), 7.39−7.44 (6H, m, Ht),
7.33−7.37 (4H, m, Hi and Hv), 7.25−7.29 (8H, m, Hk, Hq and Hu),
7.05 (1H, td, 3JH−H, H−F = 8.3 Hz, 4J = 2.6 Hz, Ho), 4.06−4.14 (1H, m,
He/f), 3.55−3.63 (1H, m, He/f), 2.04−2.17 (1H, m, Hb/c), 1.84−1.97
(1H, m, Hb/c), 1.13 (3H, t, J = 7.3 Hz, Ha) ppm. δC (100 MHz, 298
K, CDCl3): 162.9 (Ch), 161.7 (d, JC−F = 252 Hz, Cp), 155.9 (Cl),
1JC−F = 255 Hz, Cl), 161.5 (Ch), 144.6 (Ci), 139.1 (Cf), 135.4 (d, 2JC−P
= 9.4 Hz, Cp), 131.4 (d, 4JC−P = 2.4 Hz, Cr), 127.9 (d, 3JC−P = 11.5 Hz,
3
1
Cq), 127.4 (d, JC−F = 8.1 Hz, Cj), 126.5 (d, JC−P = 63.3 Hz, Co),
124.8 (d, 2JC−F = 18 Hz, Cm), 121.5 (d, 4JC−P = 4.2 Hz, Ce), 117.5 (d,
4JC−P = 4.6 Hz, Cg), 111.5 (d, 2JC−F = 23.2 Hz, Ck), 52.9 (d, 3JC−P = 4.5
Hz, Cc), 45.0 (1JC−Pt = 311 Hz, Cb) 35.0 (Ca) ppm. δF (375 MHz, 298
K, CDCl3): −109.4 (4JF−Pt = 17.5 Hz) ppm. δP (202 MHz, 298 K,
CDCl3): −5.7 (1JP−Pt = 2502 Hz) ppm. δPt (298 K, CDCl3): −2411 (d,
1JP−Pt = 2550 Hz) ppm. HR-MS (ESI): m/z 776.0941 calculated for
C33H2935Cl2FNNaP194Pt = (M + Na)+ 776.0917.
3
1
3
2
136.9 (Cj), 135.1 (d, JC−F = 8.7 Hz, Cn), 133.6 (d, JC−P = 10.6 Hz,
Ct), 129.6 (d, 4JC−P = 2.5 Hz, Cv), 127.6 (d, 1JC−P = 65.5 Hz, Cs), 126.7
(d, 3JC−P = 11.3 Hz, Cu), 125.0 (d, 4JC−P = 4 Hz, Ck), 123.7 (d, 4JC−P
=
2
2
4 Hz, Ci), 115.7 (d, JC−F = 25.5 Hz, Cq), 112.0 (d, JC−F = 21.5 Hz,
Co), 40.0 (Cg), 21.4 (Cd), 13.5 (Ca) ppm. δF (375 MHz, 298 K,
CDCl3): −110.2 ppm. δP (161 MHz, 298 K, CDCl3): −1.9 (1JP−Pt
=
1
3758 Hz) ppm. δPt (298 K, CDCl3): −3442 (d, JPt−P = 3779 Hz)
ppm. HR-MS (ESI): m/z 740.0956 calculated for
C32H2835Cl2FNP194Pt = (M − Cl)+ 740.0942, 250.0795 calculated
for C14H1435ClFN = (Ligand + H)+ 250.0793. Anal. Found
(Expected): C 49.17 (49.40); H 3.52 (3.63); N 1.74 (1.80).
Oxidation of Complex 5: Synthesis of Complexes 6, 8, and
10. Complex 5 was dissolved in CDCl3, the mixture cooled to −40 °C,
and one equivalent of iodobenzene dichloride added. By the time any
NMR spectra could be recorded, the only platinum-containing species
present was the complex identified as cis-6.
3
δH (600 MHz, 298 K, CDCl3): 7.79 (1H, t, J = 8 Hz, Hd), 7.54
(1H, dd, 3JH−F = 9.8 Hz, 4J = 2.6 Hz, Hh), 7.57 (1H, dd, 3J = 8 Hz, 4J =
1.1 Hz, He), 7.30 (1H, dd, 3J = 8.6 Hz, 4JH−F = 5.5 Hz, Hf), 7.24 (1H,
dd, 3J = 8 Hz, 4J = 1.3 Hz, Hc), 6.78 (1H, td, 3JH−H, H−F = 8.5 Hz, 4J =
2.6 Hz, Hg), 3.89 (2H, s, Hb), 1.75 (6H, s, Ha) ppm. δC (150 MHz,
3
298 K, CDCl3): 139.2 (Cd), 125.8 (d, JC−F = 9.3 Hz, Cf), 119.6 (d,
2JC−F = 21.6 Hz, Ch) 118.8 (Cc), 117.9 (Ce), 112.0 (d, 2JC−F = 23.3 Hz,
Cg), 52.7 (Cb), 27.8 (Ca) ppm. δF (375 MHz, 298 K, CDCl3): −106.9
(4JF−Pt = 62 Hz) ppm. δPt (298 K, CDCl3): −3577 ppm. HR-MS
(ESI): m/z 514.0019 calculated for C15H1435Cl2FNNa194Pt = (M +
Na)+ 514.0006.
If the reaction mixture was treated with additional iodobenzene
dichloride, a number of other new species were observed, including
complex 10, which was the only species that could be isolated via
column chromatography (eluting as the first fraction in chloroform on
silica).
δH (500 MHz, 233 K, CDCl3): 7.86 (1H, t, 3J = 7.8 Hz, Hf), 7.79−
3
7.83 (6H, m, Hk), 7.46 (1H, d, J = 7.7 Hz, Hm), 7.38−7.42 (8H, m,
Hg, Hh, and Hl), 6.79 (1H, dd, 3J = 7.7 Hz, 4J = 1.8 Hz, He), 6.70 (1H,
td, 3JH−H, H−F = 8.2 Hz, 4J = 2.2 Hz, Hi), 6.33 (1H, td, 3JH−F, H−P = 9.9
δH (400 MHz, 233 K, CDCl3): 7.97 (1H, t, J = 8 Hz, Hg), 7.87
3
(1H, dd, 3J = 8 Hz, 4J = 1.1 Hz, Hh), 7.70 (1H, dd, 3J = 8 Hz, 4J = 1.3
Hz, 4J = 2.2 Hz, 3JH−Pt = 42 Hz, Hj), 3.22 (1H, d, 2J = 8.6 Hz, 2JH−Pt
=
Hz, Hf), 7.65 (1H, dd, 3JH−F = 9 Hz, 4J = 2.5 Hz, Hk), 7.57 (1H, dd, 3J
4
3
4
43.5 Hz, Hc), 2.42 (1H, dd, 2J = 8.6 Hz, 3JH−P = 3 Hz, 2JH−Pt = 74 Hz,
Hd), 1.88 (3H, s, Ha), 0.84 (3H, s, Hb) ppm. δC (100 MHz, 233 K,
= 8.8 Hz, JH−F = 5.5 Hz, Hi), 7.02 (1H, td, JH−H, H−F = 8.4 Hz, J =
2.5 Hz, Hj), 4.96 (1H, br, Hb/c), 4.01 (1H, br, Hb/c), 1.81 (6H, s, Ha)
7262
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2010, 29, 1396. (c) Newman, C. P.; Clarkson, G. J.; Alcock, N. W.;
Rourke, J. P. Dalton Trans. 2006, 3321. (d) Petretto, G. L.; Wang, M.;
Zucca, A.; Rourke, J. P. Dalton Trans. 2010, 39, 7822. (e) Rourke, J. P.;
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Soc., Dalton Trans. 1992, 3009.
(12) Newman, C. P.; Deeth, R. J.; Clarkson, G. J.; Rourke, J. P.
Organometallics 2007, 26, 6225.
ppm. At RT the CH2 peak appears broad at 4.43 ppm. δC (125 MHz,
298 K, CDCl3): 164.2 (Ce), 141.5 (Cg), 127.0 (d, 3JC−F = 9.2 Hz, Ci),
(13) Rendina, L. M.; Puddephatt, R. J. Chem. Rev. 1997, 97, 1735.
(14) Gary, J. B.; Sanford, M. S. Organometallics 2011, 30, 6143.
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6365.
(16) (a) Powers, D. C.; Benitez, D.; Tkatchouk, E.; Goddard, W. A.,
III; Ritter, T. J. Am. Chem. Soc. 2010, 132, 14092. (b) Powers, D. C.;
Geibel, M. A. L.; Klein, J.; Ritter, T. J. Am. Chem. Soc. 2009, 131,
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Soc. 2010, 132, 14530.
123.0 (Cf) 120.6 (Ch), 118.6 (d, 2JC−F = 25 Hz, Ck), 115.2 (d, 2JC−F
=
23 Hz, Cj), 55.3 (Cb), 44.9 (Cd), 30.3 (Ca) ppm. δF (375 MHz, 253 K,
CDCl3): −101.2 (4JF−Pt = 31 Hz) ppm. δPt (298 K, CDCl3): −1148
ppm. HR-MS (ESI): m/z 583.9381 calculated for
C15H1435Cl4FNNa194Pt = (M + Na)+ 583.9389.
ASSOCIATED CONTENT
* Supporting Information
Full details of the X-ray structures and CIF files for 1a and 3a.
This material is available free of charge via the Internet at
http://pubs.acs.org.
■
S
(17) Green, J. C.; Herbert, B. J.; Lonsdale, R. J. Organomet. Chem.
2005, 690, 6054.
(18) Tobe, M. L.; Burgess, J. Inorganic Reaction Mechanisms; Addison
Wesley Longman Limited: Harlow, UK, 1999.
(19) Stille, J. K.; Lau, K. S. Y. Acc. Chem. Res. 1977, 10, 434.
(20) (a) Williams, B. S.; Holland, A. W.; Goldberg, K. I. J. Am. Chem.
Soc. 1998, 121, 252. (b) Williams, B. S.; Goldberg, K. I. J. Am. Chem.
Soc. 2001, 123, 2576.
AUTHOR INFORMATION
Corresponding Author
*E-mail: j.rourke@warwick.ac.uk.
■
(21) Khusnutdinova, J. R.; Newman, L. L.; Zavalij, P. Y.; Lam, Y. F.;
Vedernikov, A. N. J. Am. Chem. Soc. 2008, 130, 2174.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We thank Warwick University for a WPRS award to S.H.C. and
support from Advantage West Midlands (AWM) (partly
funded by the European Regional Development Fund) for
the purchase of a high-resolution mass spectrometer and the
XRD system that was used to solve the crystal structures of 1a
and 3a.
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